1. Technical Field
The present invention relates to a subminiature optical system, and more particularly, to a subminiature optical system mounted in front of an automobile to implement a telephoto angle of view.
2. Description of the Related Art
Recently, mounting of a camera, which is an auxiliary unit for securing a field of view for a driver and allowing the driver to easily drive a vehicle, has increased at the time of manufacturing of the vehicle. In addition, cameras having various resolutions have been mounted according to a mounting position thereof.
A camera for a vehicle may be divided into a front camera and a rear camera according to a mounting position thereof and be divided into a visible camera and a monitoring camera according to a use object thereof.
Among them, the camera photographing a front image should implement a telephoto angle of view, and the camera photographing a rear image should implement a wide angle of view.
Here, the camera photographing a front image is generally configured of three or four sheets of lenses, such that it requires a bright optical system capable of performing photographing even in a low illumination environment while night driving.
The bright optical system as described above is generally designed to have a configuration (that is, a triplet structure) of three sheets of lenses: a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power in order from an object side.
The configuration of three sheets of lenses as described above has advantages such as high mass productivity characteristics and a cheap cost, but also has a disadvantage such as a low resolution. Therefore, in order to improve a resolution, the second lens is divided into two sheets of lenses having positive refractive force or negative refractive force and spaced apart from each other by a predetermined interval, such that the optical system configured of a total of four sheets of lenses may be designed.
However, in this case, the entire length of the optical system may be increased. Therefore, an interval between the second and third lenses can not but be designed to be as narrow as possible, such that the possibility that scattered reflection will be generated becomes large and astigmatism and chromatic aberration become large.